Background: Persistent descending mesocolon (PDM) is a rare colonic anatomical variant. However, PDM's impact on the technical aspects and outcomes of laparoscopic colorectal cancer resection are unclear. Patients and Methods: This retrospective clinical cohort study was conducted at a high-volume cancer center in Japan to evaluate intra-and postoperative outcomes of laparoscopic colorectal cancer surgery in patients with (PDM+) or without (PDM-) PDM over the past 7 years. Results: Between January 2012 and September 2019, 2,775 patients underwent laparoscopic colorectal cancer resection at our center, including 60 (2.1%) cases of PDM. Preoperative detection was achieved in only 5 patients (8.3%), 39 patients were men, and 21 patients were women. The average age was 67 years. Twenty patients had a history of prior abdominal surgery (33.3%), with little or no subsequent adhesions. The average duration of sigmoidectomy in PDM+ patients (n=17; 217.7±14.2 min) was significantly longer than that in 176.2±2.4 min; p=0.003), as was average blood loss (32.3±10.6 ml vs. 16.7±2.8 ml; p=0.03). Likewise, average operative time for high anterior resection in PDM+ patients (n=11; 227.1±20.2 min) was significantly longer than that in 195.6±3.0 min; p=0.048). Rates of postoperative anastomotic leakage and postoperative recurrence did not differ in both groups. In PDM+ patients, retention of left colic artery had no impact on proximal specimen margins or occurrences of anastomotic leakage. Conclusion: PDM prolongs operative times and increases bleeding in laparoscopic colorectal cancer surgery and should be considered a risk factor when encountered.

Objective:Anastomotic leakage after laparoscopic low anterior resection in male rectal cancer patients with a narrow pelvis cannot be easily resolved. The objective of this study is to assess numerical information of narrow pelvis and to determine whether prediction of morbidity can be possible.Methods:Retrospective medical record review was performed. From July 2007 to January 2013, 43 consecutive male patients with low rectal cancer who underwent laparoscopic low anterior resection were divided into the anastomotic leakage–negative group and anastomotic leakage–positive group. Eleven anatomic parameters were measured from preoperative magnetic resonance imaging of pelvis and a new index called “pelvic index” was calculated.Results:The pelvic index (difference between the interspinous distance and the diameter of the mesorectum divided by the depth of the cavity of the lesser pelvis) in the leakage-positive group was significantly smaller than that in the negative group (P=0.038). Comparison between those 2 groups at the border of the cut-off value of the pelvic index (13.0) showed a significant difference.Conclusions:Preoperative assessment by the pelvic index can predict the narrow pelvis and risk of anastomotic leakage.

Background/Aim: The purpose of this study was to investigate the clinical, pathological, and prognostic differences between adenocarcinoma (ADC) and mucinous adenocarcinoma (MUC) in colorectal cancer (CRC). Patients and Methods: This was a retrospective study of a Japanese high-volume cancer Center over a 10-year period. From April 2007 to December 2016, a total of 3,296 patients with primary CRC were included in the study. The clinical characteristics of MUC and ADC were compared. Then, propensity score matching was performed according to a 1:2 ratio. Multivariate analysis was used for independent risk factors related to prognosis. The overall survival (OS) and disease-free survival (DFS) of 126 cases of MUC and 256 cases of ADC were studied, as well as the survival rate of each stage. Results: MUC accounts for 3.82% of the total CRC. Compared to ADC, MUC is more common in female patients (47.62% vs. 38.77%; p=0.045), with higher carcinoembryonic antigen levels (56.35% vs. 34.95%; p<0.001), more ulcerative and infiltrative types (82.54% vs. 72.93%; p=0.016), higher incidence of perineural infiltration (51.59% vs. 41.04%; p=0.018), deeper infiltration (T3-T4: 90.48% vs. 65.84%; p<0.001), and more advanced cancer (stage III-IV: 59.52% vs. 44.79%; p=0.001). MUC is also more likely to recur (24.6% vs. 14.32%; p=0.001). Regarding the long-term survival rate, the OS (p<0.001) and DFS (p=0.05) is consequently worse. After propensity score matching, multivariate analysis showed that MUC was a common independent risk factor for DFS [odds ratio (OR)=4.277; 95% confidence interval (CI), 0.327-0.97; p=0.039], and also for OS (OR= 6.836; 95% CI, p=0.009). In MUC, OS and DFS were still relatively worse (OS: p=0.017; DFS: p=0.038). However, only significant statistical differences were shown in stage II (OS: p=0.003; DFS: p=0.007). No significant differences were noted in the stages I, III, or IV. Conclusion: MUC is a high-risk factor for stage II CRC. Adjuvant chemotherapy should be routinely recommended for patients with MUC stage II, and special attention should be paid during their follow-up.According to European and American guidelines, patients with a high risk of recurrence after radical surgery for stage II colorectal cancer (CRC) should receive adjuvant chemotherapy (1, 2). However, the definition of "high risk" varies. Mucinous adenocarcinoma (MUC) is defined as a high-risk factor in United States guidelines, but not in European guidelines. In Japan, clinical trials of conventional postoperative adjuvant chemotherapy for stage II CRC have not been found to be successful (3). In 2019, there are few Japanese guidelines for the treatment of stage II rectal cancer using adjuvant chemotherapy (4). There are also different opinions on whether or not adjuvant chemotherapy is required for patients with postoperative stage II MUC.MUC is a rare tumor classification of CRC. This type of tumor contains neoplastic cells that produce a large amount of extracellular mucin. Histological markers require more than 50% of the tumor...

Background: It is not clear whether stage II colon and rectal cancer have the same risk factors for recurrence. Thus, the purpose of this study was to identify the risk factors for postoperative recurrence in stage II colorectal cancer. Patients and methods: We retrospectively analyzed the data of 990 patients who had undergone radical surgery for stage II colorectal cancer. Patients' pathological features and characteristics including age, sex, family history, body mass index, tumor diameter, gross type of tumor, infiltration degree (T3/T4), tumor grade, perineural invasion, vascular invasion, lymphatic invasion, pathologic examination of lymph node number, and preoperative carcinoembryonic assay (CEA) level was compared between patients with and without recurrence. Finally, the prediction of the left and right colons was analyzed. Results: The mean ages of the colon cancer and rectal cancer patients were 69.5 years and 66.4 years, respectively. In total, 508 (82.1%) and 285 (76.8%) patients were treated laparoscopically for colon cancer and rectal cancer, respectively, with median follow-up periods of 42.2 months and 41.8 months, respectively. Forty-four recurrences occurred in both the colon cancer (7.1%) and rectal cancer (11.9%) groups. The preoperative serum CEA level and T4 infiltration were significantly higher in recurrent colorectal cancer patients. The postoperative recurrence rate of left colon cancer (descending colon, sigmoid colon) was higher than that of right colon cancer (cecum, ascending colon, transverse colon) (OR 2.191, 95% CI 1.091-4.400, P = 0.027). In COX survival factor analysis of colon cancer, the left colon is one of the independent risk factors (risk ratio 5.377, 95% CI 0.216-0.88, P = 0.02). In disease-free survival (DFS), the left colon has a relatively poor prognosis (P = 0.05). However, in the COX analysis and prognosis analysis of OS, no difference was found between the left colon and the right colon. Conclusion: Preoperative CEA and depth of infiltration (T4) are high-risk factors associated with recurrence and are prognostic factors in stage II colorectal cancer. Left colon is also a risk factor for postoperative recurrence of stage II colon cancer.

No abstract

A 66-year-old woman had been receiving follow-up since 1990 for hyperplastic polyposis, which remained unchanged endoscopically and radiologically. In 1999, a small (28 x 22 mm) superficial adenocarcinoma was detected in the ascending colon. Histologically, this was a hyperplastic polyp containing a well-differentiated adenocarcinoma invading into the submucosa. A review of the English and Japanese literature identified 32 cases of "hyperplastic polyposis." In about half of the 32 cases, an adenocarcinoma was also found amongst the hyperplastic polyps. Half of the adenocarcinomas were located in the right colon. Although hyperplastic polyposis is uncommon, it warrants regular surveillance, as it appears to be associated with an increased risk of colorectal cancer.

No abstract

Background: Unlike the tumor nodes metastasis (TNM) lymph node classification, based solely on counts of nodal metastases, the Japanese system of classifying colorectal carcinoma (CRC) focuses on regional lymph node spread. In this study, we explored the prognostic utility of inferior mesenteric artery (IMA) apical lymph node (APN) metastasis. Patients and Methods: This was a retrospective study of patients with stage III left-sided CRC. All enrollees were subjected to D3 resection between April 2007 and December 2016 at the International Medical Center of Saitama Medical University and then stratified by histologic presence (APN+ group) or absence (APN− group) of tumor in APNs examined postoperatively. Ultimately, propensity score matching was invoked (1:2) and COX regression analysis was conducted, determining group rates of relapse-free survival (RFS) and cancer-specific survival (CSS). Results: A total of 498 patients were studied, grouped as APN+ (19/498, 3.8%) or APN− (479/498, 96.2%). Prior to matching, the APN+ (vs. APN−) group showed significantly more lymphatic involvement (73.7% vs. 47.8%; p=0.023), deep (T3/T4) tumor infiltration (100% vs. 78.9%; p=0.024), and nodal metastasis (N2: 84.2% vs. 27.6%; p<0.001). In addition, para-aortic nodal recurrences were significantly increased (15.7% vs. 2.0%; p<0.001), conferring worse RFS (p<0.001) and CSS (p=0.014) rates. Once baseline factors were matched, the two groups appeared similar in RFS (p=0.415) and CSS (p=0.649). Multivariate regression analysis indicated that elevated carcinoembryonic antigen (CEA) level and deep tumor infiltration were independent risk factors for RFS, whereas postoperative complications and tumor-positive node counts were independent risk factors for CSS. APN+ status was not a significant risk factor for RFS or CSS. Conclusion: APN positivity may thus constitute a regional rather than systemic manifestation. The TNM staging based on the number of metastatic lymph nodes seems to be more reasonable than the regional lymph node classification method. Patients and Methods As candidates for this retrospective analysis, a total of 2,457 patients underwent surgical resections of left-sided CRC at the International Medical Center of Saitama Medical University between April 2007 and December 2016. Exclusion criteria were as follows: 1) recurrent 2981 This article is freely accessible online.